1. Technical Field
The present embodiment relates to electronic circuits, and particularly to an electronic circuit for facilitating a computer system when waking up from a sleep state.
2. Description of Related Art
A conventional computer system has a power supply which converts an alternating current (AC) signal (120 VAC, 60 Hz, as commonly found in the United States) to appropriate direct current (DC) signals required for the operation of a motherboard of the computer system. For raising a conversion efficiency of the power, a DC/DC converter is used in the computer system, as disclosed in U.S. Pat. No. 7,547,996.
In another aspect, for saving power, computers are increasingly conforming to the Advanced Configuration and Power Interface (ACPI) specification. The ACPI defines different processor power states, such as a normal state C0, and sleep states C1, C2, and C3. For example, when in C0 state, a CPU can execute instructions or move data. After the computer has been idle for a predetermined period, the CPU enters one of the sleep states C1, C2 or C3 in which power is saved. The sleep state C3 offers improved power saving over the sleep states C1 and C2. The sleep state C2 offers improved power saving over the sleep state C1.
However, when the computer system enters into the sleep state C3, the DC/DC converter often wrongly enters into an under voltage protection state if an input of the DC/DC converter decreases slower than an output of the DC/DC converter decreases. When the DC/DC converter enters into the under voltage protection, the computer system cannot be woken up to the normal state C0 from the sleep state C3.
Therefore, there is room for improvement within the art.